The subject invention is directed toward the valve art and, more particularly, to an improved pressure relief valve.
The invention is particularly suited for embodiment in an adjustable low pressure relief valve and will be described with special reference thereto; however, the invention is capable of broader application and could be incorporated in a variety of types and styles of check valves and pressure relief valves.
In commonly assigned U.S. Pat. No. 4,530,373 to Carl Bork et al. there is disclosed a pressure relief valve design which is particularly adapted for use in high pressure applications. Although the design can be used in low pressure applications, it incorporates a relatively small diameter valve element. In low pressure applications this small diameter results in a comparatively small area against which the upstream pressure can act for generating the opening force. As a consequence, the opening force is relatively small. With small forces available for opening the valve, it is difficult to assure that the valve will open consistently at the desired pressure setting. That is small changes in spring force, friction, valve sticking, etc. will produce significant changes in the pressure at which opening takes place.
It has, accordingly, been considered desirable to provide a pressure relief valve design which assures consistent operation throughout a wide range of low pressure settings.